The interaction of thin-film flow, bacterial swarming and cell differentiation in colonies of Serratia liquefaciens

The rate of expansion of bacterial colonies of S. liquefaciens is investigated in terms of a mathematical model that combines biological as well as hydrodynamic processes. The relative importance of cell differentiation and production of an extracellular wetting agent to bacterial swarming is explored using a continuum representation. The model incorporates aspects of thin film flow with variable suspension viscosity, wetting, and cell differentiation. Experimental evidence suggests that the bacterial colony is highly sensitive to its environment and that a variety of mechanisms are exploited in order to proliferate on a variety of surfaces. It is found that a combination of effects are required to reproduce the variation of bacterial colony motility over a large range of nutrient availability and medium hardness

Gravitational waves from three-dimensional core-collapse supernova models: The impact of moderate progenitor rotation

We present predictions for the gravitational-wave (GW) emission of three-dimensional supernova (SN) simulations performed for a 15 solar-mass progenitor with the Prometheus-Vertex code using energy-dependent, three-flavor neutrino transport. The progenitor adopted from stellar evolution calculations including magnetic fields had a fairly low specific angular momentum (j_Fe <~ 10^{15} cm^2/s) in the iron core (central angular velocity ~0.2 rad/s), which we compared to simulations without rotation and with artificially enhanced rotation (j_Fe <~ 2*10^{16} cm^2/s; central angular velocity ~0.5 rad/s). Our results confirm that the time-domain GW signals of SNe are stochastic, but possess deterministic components with characteristic patterns at low frequencies (<~200 Hz), caused by mass motions due to the standing accretion shock instability (SASI), and at high frequencies, associated with gravity-mode oscillations in the surface layer of the proto-neutron star (PNS). Non-radial mass motions in the post-shock layer as well as PNS convection are important triggers of GW emission, whose amplitude scales with the power of the hydrodynamic flows. There is no monotonic increase of the GW amplitude with rotation, but a clear correlation with the strength of SASI activity. Our slowly rotating model is a fainter GW emitter than the non-rotating model because of weaker SASI activity and damped convection in the post-shock layer and PNS. In contrast, the faster rotating model exhibits a powerful SASI spiral mode during its transition to explosion, producing the highest GW amplitudes with a distinctive drift of the low-frequency emission peak from ~80-100 Hz to ~40-50 Hz. This migration signifies shock expansion, whereas non-exploding models are discriminated by the opposite trend.Comment: Added new figure, figure 9. Updated figure 9, now figure 10. Modified the discussion of the proto-neutron star convection. Added a figure showing the average rotation rate as a function of radius. Added a section discussing where the low-frequency gravitational waves are generated, this information is visualized in figure 9. We also made some minor changes to the text and selected plot

Xanthomonas campestris pv. campestris race 1 is the main causal agent of black rot of Brassicas in Southern Mozambique

Severe outbreaks of bacterial black rot caused by Xanthomonas campestris pv. campestris (Xcc) were observed in Brassica production fields of Southern Mozambique. The causal agent of the disease in the Mahotas and Chòkwé districts was identified and characterised. In total, 83 Xanthomonas-like strains were isolated from seed samples and leaves of cabbage and tronchuda cole with typical symptoms of the disease. Forty-six out of the 83 strains were found to be putative Xcc in at least one of the tests used: Classical biochemical assays, enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies, Biolog identification system, polymerase chain reaction (PCR) with specific primers and pathogenicity tests. The ELISA tests were positive for 43 strains. Biolog identified 43 strains as Xanthomonas, but only 32 as Xcc. PCR tests with primers targeting a fragment of the hrpF gene were positive for all 46 strains tested. Three strains were not pathogenic or weakly pathogenic and all other strains caused typical black rot symptoms in brassicas. Race type differentiation tests revealed the Xcc strains from Mozambique as members of race 1. The prevalence of this pathogenic race of the Xcc pathogen in Mozambique should be considered when black rot resistant cultivars are evaluated or introduced into the production regions of this country

Correlates of physical activity for adults with disability

INTRODUCTION: This study was designed to determine factors that influence the physical activity level of adults with disability as identified in a large representative sample of U.S. adults. METHODS: Data were taken from the District of Columbia and the 12 states that administered the Quality of Life and Caregiving Module of the 2001 Behavioral Risk Factor Surveillance System. Adults with disability (n = 4038) were defined as those who required special equipment because of a health problem or who required the assistance of another person either for their personal care or routine needs. Adequate physical activity was defined as meeting the Centers for Disease Control and Prevention and American College of Sports Medicine recommendation of at least 30 minutes of moderate activity per day at least 5 days per week. Unadjusted and adjusted odds ratios were computed for demographic, health status, health care access, and health behavior variables. RESULTS: Only one fourth of the study population met the recommendation for moderate activity level. African American race, age of 50 years or older, annual income of $50,000 or higher, and being in good, fair, or poor health were all significantly related to activity level; sex, education level, health care access, and years of disability were not. CONCLUSION: Adults with disability are not meeting basic recommendations for physical activity. Some correlates of physical activity found in general populations are also related to activity level for people with disability (age, general health, race), whereas others (sex, education level) are not. These factors should be considered when planning physical activity interventions for people with disability

Quantitative effects of medium hardness and nutrient availability on the swarming motility of <i>Serratia liquefaciens</i>

We report the first controlled measurements of expansion rates for swarming colonies of Serratia liquefaciens under different growth conditions, combined with qualitative observations of the organization of the colony into regions of differentiated cell types. Significantly, the results reveal that swarming colonies of S. liquefaciens can have an increasing expansion rate with time. We compare and contrast the expansion rate results with predictions from a recent mathematical model which coupled key hydrodynamical and biological mechanisms. Furthermore, we investigate whether the swarming colonies grow according to a power law or exponentially (for large times), as suggested by recent theoretical results

Investigation of DC-8 nacelle modifications to reduce fan-compressor noise in airport communities. Part 4 - Flight acoustical and performance evaluations, for period May 1967 - October 1969

Flight acoustical and performance evaluations of DC 8 nacelle modifications to reduce fan-compressor noise in airport communitie

Decreasing the Peril of Antimicrobial Resistance Through Enhanced Health Literacy in Outpatient Settings: An Underrecognized Approach to Advance Antimicrobial Stewardship

© 2020, The Author(s). Globally, antimicrobial resistance (AMR) is a serious problem causing 700,000 deaths annually. By 2050, AMR is expected to cause approximately 10 million deaths globally each year if allowed to increase at the present rate. Many individuals have limited knowledge regarding appropriate antibiotic use and AMR. Most antibiotic use occurs in the outpatient setting, with approximately 30% of antibiotics prescribed deemed unnecessary. Antimicrobial stewardship (AMS) is a means to reduce inappropriate antibiotic use and AMR. While existing AMS efforts generally focus on the inpatient setting, a significant gap is present in the outpatient setting. A common theme across various national action plans to reduce AMR is the need for education and awareness. The importance of communicating information in a manner easily comprehended by the patient in addition to productive clinician–patient dialogue cannot be overestimated. Enhancing the public’s and patients’ AMS health literacy is an underrecognized approach to help address AMR. We describe Four Core Elements of Enhancing AMS Health Literacy in the Outpatient Setting, utilizing the Centers for Disease Control and Prevention’s framework: (1) leadership commitment, (2) intervention/action, (3) tracking/reporting, and (4) education/expertise. We call upon leaders in outpatient settings to embrace this approach to curb inappropriate antimicrobial use

Search For Trapped Antihydrogen

We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally.Comment: 12 pages, 7 figure

Antihydrogen formation dynamics in a multipolar neutral anti-atom trap

Antihydrogen production in a neutral atom trap formed by an octupole-based magnetic field minimum is demonstrated using field-ionization of weakly bound anti-atoms. Using our unique annihilation imaging detector, we correlate antihydrogen detection by imaging and by field-ionization for the first time. We further establish how field-ionization causes radial redistribution of the antiprotons during antihydrogen formation and use this effect for the first simultaneous measurements of strongly and weakly bound antihydrogen atoms. Distinguishing between these provides critical information needed in the process of optimizing for trappable antihydrogen. These observations are of crucial importance to the ultimate goal of performing CPT tests involving antihydrogen, which likely depends upon trapping the anti-atom

The Presampler for the Forward and Rear Calorimeter in the ZEUS Detector

The ZEUS detector at HERA has been supplemented with a presampler detector in front of the forward and rear calorimeters. It consists of a segmented scintillator array read out with wavelength-shifting fibers. We discuss its desi gn, construction and performance. Test beam data obtained with a prototype presampler and the ZEUS prototype calorimeter demonstrate the main function of this detector, i.e. the correction for the energy lost by an electron interacting in inactive material in front of the calorimeter.Comment: 20 pages including 16 figure